Hydraulic press



omu 10,1944. l.. NERSEN 2,360,060

HYDRAULIC PREss l l Filed Aug. 6, 194]. .3 Sheets-Sheet 2 ToPRE-F/LLER37 3,0

` Oct. 10, 1944.

L. IVERSEN HYDRAULIC PRESS Filed Aug. 6, 1941 5 Sheets-Sheet 3 ToPRESSURE CYLINDER Efj-.

To Put.;- BA ck CYuNoERs 9 10 To PREfFlLLER INVENTOR Lorenz Aye/"Senmadw BRA m: HORSE' Powe-R y use.

on the line III- III of Figur l; l

Patented oci. 1o, :1944

nynaauucrnnss Lorenz Iverson, Pittsburgh, Pa., assigner to Mesta MachineCompany, Pittsburgh, Fa., a oorporation of Pennsylvania ApplicationAugust o, 194i, serial No. 105,639

(ci. s0-52) 2 Claims.

This invention relates to hydraulic presses'. It provides a novelmechanism whereby the ilexibility of operation is greatly increased withmarked improvement in output. Material simpliiication ,of theinstallation and, in certain cases, very substantial reductions in costare also obtainable.

Heretofore hydraulic presses, particularly in the larger sizes, havebeen eithery of the socalled steam hydraulic type or the straighthydraulic type with reciprocating pumps. In

the. steam hydraulic type, the hydraulic pressure is produced byintensifiers receiving pressure from steam boilers. In the straighthydraulic type, several'rnotoror steam-driven reciprocating pumps areconnected in parallel to the press cylinders. press head is obtained bycutting the press cylinders in or out, the line pressurebeing constantat all times. In these prior presses, theA press head is raised byauxiliary hydraulic cylinders called pullbacksJ Idle strokes areeffected by the force of gravity which comes into play when the pressureon the pullback cylinders relieved.

The presses `iust described .have` very little flexibility and theiroutput has been seriously limited. They are necessarily designed vforthe heaviest work and are correspondingly slow. On lighter work vtheyoperate at a speed far less than the ability of the workmen tomanipulate the workpiece. 4

In my improved system, I depart entirely from the principle of the oldstyle press systems and employ pumps of the vcentrifugal type which arewithout positive displacement in contrast t the intensiers andreciprocating pumps` in 'common I arrange these pumps in series and inthis fashion and with the related structures herein described, I havebeen able to use them with entire success and with the improvements inoperation above noted. I am able to obtaina variable line pressure byemploying the pumps in. series-and by using pumps having thecharacteristic of' delivering maximum pressure at shut-0E (zerocapacity), I can obtain a very rapid press operation. I

In the accompanying drawings illustrating c. present preferredAembodiment of the invention:

Figure 1 is a top plan view of a hydraulic press` and its fluid-supplysystem;

Figure 2 is a front elevation of the press per se;

Figure 3 is a vertical section to enlarged scal In both types, variablepressure of the p Figure 4 is a diagram showing the control system; and

"Figure 5 is a chart showing the characteristics of one of the pumpsemployed; i

Referring first to Figure 2, there is shown a hydraulic press having abase 2 and a head 3 con nected by vertical' posts t. The base carries aplaten 'or accommodating the workpieces and a cross-head 5 is arrangedto move vertically toward and away from the platen 5, being guided byslides 1 on the posts t. .The head 3 is bored to provide a cylinder 8arranged Ain the vertical center line of the press. A piston in thecylinder is secured to the cross-head 6. Lifting cylinders 9 and i0 aredisposed at the ends of the press and have pistons il therein bearing onshoulders i.

i2 on the cross-head t. The cylinders 9 and i0 serve to return thecross-head after a working stroke eected by the cylinder 8.

The cylinders 9 and iii are connected t0 a pipe il leading from acontrol station indicated generally at S in Figure l and hereinafterdescribed in detail. A pipe i8 connects the cylinder 8 to the controlstation S.

The control station is shown in diagram in Figure 4. In this diagram thevalves have been indicated conventionally, but it will be understoodthat at the pressures which may be ernployed and with the volumeof waterto be controlled, it will generally be necessary to use power-actuatedvalves withmanual controls for the valve-actuating mechanism. The pipeil, which supplies the cylinders t and iii, is connected through a 3-wayvalve 2i to a supply pipe 22. Ordinarily theA valve 2i remains open andwater is supplied to the pipe 22 under constant pressure so that thecylinders t and ill constantly urge the cross-head .6 of the pressupwardly.

The valve 2| may be shifted to connect the pipe il to the supply pipe 22or toa discharge pipe 23, as desired.

The pipe i8 is connected to a T 26. The T 2S connects the pipe i8,through a valve 2l, to. a supply pipe 28. The T 26 also connects thepipe it, through a valve 29, to a discharge pipe 30. Ii? the valve 29 isclosed and the valve 2l opened, luid under pressure passes to the T 26and thence to the main press cylinder 8, overcoming theforce of thelifting cylinders 9 and it, and eiiecting a working stroke of the press.f

the pump.

ment of the cross-head to effect automatic stroking.

The water for 'the cylinders s, s, 'and 1u is taken from a prelller tank91 operatingunder a low head, say, 40 to 1004 pounds per ,square inch.tank has an air space above the water level so as to accommodate thevarying quantitiesy of Water which are supplied to it in operation./Make-up` waterv is supplied to the tank 4under pressure through a valvedsupply pipe 98, but in general the system is a circulatory one, thewater being discharged from the cylinders back to the preller throughthe pipes 23 and 80. A pump v'99 supplies waterfrom a sump 40 to thepreilller through a pipe 39a.

Water fromI the preflller 91 'passes through a pipe, 4i to a cooler 42consisting of 4a pipecoil having a water vjacket provided with pipes 43,

whereby cooling water may be circulated through the-jacket. The waterpasses from the cooler 42 through a pipe 45 vterminatingin the inlet 45of acentrifugal pump 41. The outlet of theY rpump `41 is connectedthrough a pipe 48 to the attempted to circulate it through the pump and'letting -the pump idle. Indeed, in manycases, it may not be feasible tocirculate water through the idle .pump at all. v A

Figure 5 shows the characteristics of the pumps above described. It willbe noted therefrom that the pumps deliver maximum head at zero capacityand that only a'. slight drop/in pressure,occurs when delivering at fullrated volume. By way of example, the pumps 41, 49, and 5I delivermaximum heads of approximately 1250, 1250, and 2000 pounds per squareinch, re-

vspectively, so that by using pumps 41 and 49 in series, a workingpressure of 2500 pounds per square inch is obtained and by using allthree pumps in series a wo king. pressure of 4500 Y pounds per squareinch is obtained. Whatever inlet of a Icentrifugal pump 49. Y The outletof;

the pump 49 is, in turn, -connected through a pipe 50 to the inlet of acentrifugal pump 5|. Its

outlet is connected through a pipe 52 and a check working pressure isused, the cylinder 8 easily overcomes the cylinders 9 and I0 because thetotal cross sectional area of the former is very much greater than thesum of those of the latter. The valve 2|, however, may be shifted to itssecond position to connect the pipe I1 to the pipe 23. The cylinder 8then has to overcome only the preflller pressure in the cylinder 9 andI0, instead of the main working pressure, therev alve 53 to the pipe 28leading to the control' station S. A branch pipe 54 leads from the'checkvalve 53 to a pair of accumulator-bottles 55 providing an air cushionfor the system. An-

air compressor 58 is provided for supplying air as required to thesebottles through a connecting pipe-(not shown).

The pumps 41, 49, and 5I are each independently driven by motors 51, 58,and 59, respectively, and these motors are .separately controlled byswitches 80, 8i, and 62, respectively, at the control station S. It willbe noted that the pumps arearranged in series so that by actuating one,,two or three of them, as may be desired, three stages of pressures haybeobtained, for example, .stages of 1250, 2500 and 4500 pounds persquareiinch. y

The pumps employed are of the'multi-stage l centrifugal type. In orderto minimize the prespumps are operating. Thus the speed o'f the presssure drop in the system, I provide for bypassingv any idle pump or pumpsthrough mechanism shown in detail in Figure 3.

Referring to Figure 3, the :pump casing is -indicated at 83. It issurmounted by a check valve body 84 having a vertical bore 85which-registers with the inlet 86 of the pump. The inlet 48 communicateswiththis bore. At its upper end the boreleads to a horizontal bore 81,but communication between the two is shut olf when the pump is runningby a check valve 88. Water entering the inlet 48, therefore, passesdownwardly through the bore 55 into the inlet 88 of The pump` dischargesthe water at materially higher pressurethrough the discharge port 89into a vertical bore 10 in the valve'body 54. 'I'he bore 18 communicateswith the horizontal bore 81. Water discharged from the pump is,l asstated, at a materially higher pressure than thewater entering throughthe inlet `48 and the check'valve 88 is therefore held closed. Thewater-is finally discharged from the pump through an outlet 12communicating` with -the pipe 48, 50 6112, as the case may be. f

In case a pump is standing idle, water entering through its inlet raisesthe valve 58 and passes through the horizontal bore 81 directly totheoutlet 12,1thus saving the material loss of head which wouldbeencountered ii it were head is substantially pressure employed.

Numerous advantages are obtained by my inthe same regardless of thevention. One of the primary ones is simplicity of control. Another isthe speed with which the head can be moved from its top position'intoengagementwith the work. This is due to the fact that the pumps aredelivering maximum pressure with the valve 21 closed, and thatsubstantially maximum pressure is immediately imparted to the workingcylinders when the .Valve is opened. This gives speedy idling and rapidstroking during the working of the press. A further advantage is that myimproved press'has greater flexif bility o f operation and that as soonas the workers' vbecome skilled in its -use they can accomplish farvmore with it than with ordinary presses.

I have illustrated 4and described a present pre ferred embodiment of theinvention. It will be understood, however, that this is by way ofillustration only and that it may be otherwise emboiieldiithin theAscope Aoi" the following claims.

1. A hydraulic press comprising a m'ovable press Y head, a pressurecylinder having a plunger therein connected to the press head, a watersupply pipe leading tothe cylinder, a plurality of` centrifugal pumpshaving the characteristic of delivering substantially lmaximum head atzero capacity, the pumps being connected in series to the supply pipe,motors for individually driving the several pumps, separate controls'for each motor-whereby a pump may be controlled at /will independentlyof the control of any other pump and the line pressure thereby varied, aby-'pass around at least one pump having a check-valve therein landV ashut-off valve in the supply pipe between the cylinder and the pumps. 4

A hydraulic press comprising a movable Y A'controlled at willindependently of the control of any other pump and the line pressurethereby vvaried, a by-pass around atleast oneof the press head, apressure cylinder having a plunger therein connected to the press head,a water supply pipe leading to the cylinder, a plurality of multi-stagecentrifugal pumps .having the characteristic' of deliveringsubstantially maxi- .mum head at zero capacity. the pumps beingconnected in series to the supply pipe, motors for individually drivingthe several pumps. separate controls for each motor whereby a pump maybe pumps having a check-valve therein movable to closed position whenthe pump with which 'the by-pass is associated is in operation butmovable to open position when not subject to the pressure generated bysaid pump, whereby the by-pass

